Marking arrangement for final selector switches



Nov. 7, 1950 D. P. LONG MARKING ARRANGEMENT FOR FINAL SELECTOR SWITCHES Filed April 25, 1946 2 Sheets-Sheet 1 Inventor DOUGLAS PERCY LONG A llorney D. P. LONG 2,529,471

MARKING ARRANGEMENT FOR FINAL SELECTOR SWITCHES Nov. 7, 1950 2 Sheets-Sheet 2 Filed April 25. 1946 Inventor DOUGLAS PERCY LONG y e H r 0 I. I. A

Patented Nov. 7, 1950 MARKING ARRANGEMENT FOR FINAL SELECTOR SWITCHES Douglas Percy Long, Chislehurst, England, assignor to Siemens Brothers & Co. Limited, London, England, a British company Application April 25, 1946, Serial No. 664,963 In Great Britain May 4, 1945 6 Claims.

This invention relates to automatic telephone systems and more particularly to final selectors in such systems. It has especially in view improved arrangements for the setting of a 200- outlet final selector by the marking method.

- Selecting switches have been proposed in which the outlets are connected in paired contact arcs, two'arcs of a pair being associated with different ends of a wiper which in the movement of the selector pass over. the two arcs in succession, one end of the wiper entering its associated arc of contacts when the other end of the wiper leaves its associated arc Of contacts. rangement provides the equivalent of an arc containing twice the number of contacts. The number of wipers and contact arcs may be included in two sets connectible over contacts of a wiper switching relay thereby doubling the number of outlets connected to the selector. In this way 200 outlets may be had from a selector furnished with arcs of 50 outlets each.

In the present invention a final selector of this kind is used and it is a feature of the invention that for marking purposes a single arc of contacts containing as many contacts as there are in one of a pair of arcs is employed, the contacts in the marking are being individually connected to as many contacts on a marking switch or other selective marking device. A single marking contact on the selector therefore serves for the marking of four outlets, one in each arc of a pair in each set of arcs. The wiper associated with the marking arc of the selector is of the ordinary double-ended kind in which both ends sweep over the same contacts in succession.

In the case of a 200-line final selector the marking in respect of the tens digit is common to two values of that digit and difierentiation between them is efiected on that basis. Differentiation between the same digital value in two hundreds groups may be efiected by means of a signal re,

ceived at the time the final selector is taken into use or any other difierentiating condition such as between two paths of entry may be used. The differentiation in one case takes the form of a wiper switching operation and in the other case it takes the form of a preliminary movement of the selector wipers over one arc of a pair to bring, them to a predetermined contact position at the commencement of the other are of the pair. The preliminary movement may take place on seizure of the final selector if this movement is utilised for difierentiating between hundreds groups or it may be delayed until the tens digit has been received; The difierentiating signal may con- This arsist-of the application or non-application of a potential to one of ,the speaking wires at the preceding selector whereby a discriminating relay in the final selector is operated or prevented from operating. The operation or non-operation of the discriminating relay may, by itself or by means of another relay controlled by it, prepare or close driving and test circuits for the selector, the test circuit being completed immediately to prevent movement of the selector wipers or as a result of the wipers being driven to the predetermined contact position. The closure of the test and driving circuits may be delayed until the tens digit has been received whereupon a steering relay may be operated to complete circuits prepared according to the condition of the discriminating relay. The operation of the steering relay may take place immediately after the release of the relaythat determines the end of an. impulse train, generally called the dialling relay, if no preliminary movement of the selector wipers is required or it may be delayed until the wipers have reached the predetermined contact position. The steering relay is conveniently operated in series with the test relay in the circuit controlling the preliminary movement of the selector.

The registration of the tens impulse train may determine whether wiper switching is required or not and the marking device as set by the tens digit may open or close a circuit for the wiper switching relay accordingly. The two digits concerned in the setting of the final selector may be registered on two single motion digit switches of 10 outlets each, contacts of the tens digit switch being connected in pairs to wipers of the units digit switch the contacts of which are connected to the 50 contact marking arc in the selecting switch. It is convenient that the pairing of digits of the hundreds groups should be on an odd and even basis, and that of the tens group, the digits 1 and 6, 2 and 7 and so on should be paired. The initial operating circuit for the dialling relay may include normal contacts and wipers of both digit switches and a back contact of the steering relay while for its re-operation prior to receipt of theunits digit the operating winding of thedialli-ng relay is connected over a front contact of the steeringrelay and the normal contact and-wiperof the units digit switch. The wiper switching relay may be connected to appropriate contactsin an arc of the tens digit switch.

,Thefinal selector besides being suitable for selection of any one. of 200 individual outlets may, bythe provision of additional wipers and con- The contacts in the additional arcs i are commoned to the contact in the markingarc y of the selector that would be marked by the number allotted to the P. BsX groupasa whole double-ended type of which both ends traverse the same are of contacts and XI and X2 are wipers associated with arcs in which lines of P. B. X groups are connected, wiper XI being of the same type as the speaking and test Wire wipers andi ipeIjTXZ bein'giaj s'ingle e'nded wiper normally positioned at' -the commencement of the full line arc. Each arc comprises a normal contact, 50 contacts connected to outlets and a last contact. --.The contact in the normal position in the broken line arcs is one to which the selector wipers are automatically rotated in accordance 'with 'a signal denoting that a particular and conveniently termed the'firstline'; 'In this way a P. B. X group may consist of from 2to"50 lines, all the lines of a group being conhectedini the same are, but not necessarily in consecutive order, i. e. they may appear anywhere in the are,

hundreds group is required and is hereinafter referredtoas'the predetermined contact. In the ,test wire arcs this contact is connected to a cirinterspersed with lines of other P. B. X'groups or individual lines if need be.

The last contacts-ineach test arcare connected to a circuit for 'a-last-conta6t relay and-taper mit the selector wipers in their preliminary move ment to pass these contacts, it may be arranged that the circuit -for the last contact relay is only connected up when the selector wipers are positioned at the commencement of the arc in which selection is to be made, the test circuit 'including a contact in the common *markingarc. The impulse receiving relaymay be of low impedance and for the-reversion of tones to the caller it may be substituted by a high impedance relay over which balanced tone-currents maybe reverted.

Provision may be made for registering unsuccessful calls to one line or group of lines connected in each arc of the finalselector.

The digit switches and -control relays may be included in a common control circuit, the only relays in the individual selector circuit being a coupling relay and I the switching and wiper switching relays.

The arrangements of the invention areespecially suitable for use with a high speed uniselector with individual motor drive.

Reference will now be had to theaccompanying drawings which show by way of example an embodiment of the invention. i

The drawings show, inl ig. 1,'the circuit of a final selector and in Fig. 2a common control circuit for the control of a final selector of the kind shown in Fig. l, and'in'Figfi3 amodificatioi' to the circuit for registering unsuccessful calls. The final selector illustrated isa single-motion motor-driven switch having 200 outlets of which outlets in one hundreds group are connected' in the arcs shown in full lines and the outlets of the other hundreds group are "connected in-the arcs shown in broken lines. Thearcs containing outlets of a hundreds group aredivided into two, one are of 50 outlets being accessible" over back contacts of a wiper switching relay and the other are of 50 outlets being connected over front contacts of the wiper switching relay. The contact bank of the selector comprises 1 6 arcsof'52 contacts each, the arcs, with the excep'tionof the two shown lowermost, being paired, the'two arcs of a pair being traversed respectively "by the 'two ends of a wiper in succession, the ends of the wipers shown in broken linesentering 'the broken line arcs when the ends-or the wipers shown'in" full lines leave the fullline' arcs. The wipers 'are designated +"and Pffor 'the "negative and positive speaking wireywipers and the test wipers respectively.' M amarking wiper of "the J .cuit for stopping the selector in this position and in the arc of wiper M the contact is connected to'the last contact for stopping the switch in the last contact position. Conta/cts in the arc of wiper M'corresponding to the first lines of PL'BLX groups are also connected inithe -arc's' of wipers XI and X2 to contacts corresponding in position to all the linesof their'respectivegroups and'it may here be remarked thatP. B. X' lines may appearin any position in 'one hundreds group, that connected to the full linearcs', but only in the outlets in the other hundreds'group reached in response to a tens digit-of -value"0 to 4, i. e. in the broken line are of Wiper-XI.

If selection is to be-exercised in the hundreds group connected'to the fullfline arcs a signal will:

be received from the preceding 'swi'tching stage to prevent movement 'ofthe selector after receipt of the tens digit. If selection is to be exercised in the hundreds group conn'ected' to the'broken line arcs, no signal willb'e receivedfrom the pre'-' ceding switching "stage "and afte'rthe tens digit has been received the selector will "be driven to the predetermined contact position; The tens digit will determine flwhether wiper switching is required or not; a tens digit of from -l to'4 and 10 impulses will not require wiper switching while this latter operation will'be performed on receipt of 'a-tens'idigit'of from 5 to 9 impulses. The selector is drivenby an individual electric motor under thecontrol of "a magnet,:the driving mecha-' nism being represented generally :'by the magnet MU. The switch has two1ofin'orma1 contacts designated NI and N2 respe'cti vely whichare' operated when the wipers 'leavetheir normal position. Beside 'the' wiper 'switc'hing relayalready ref erred to which is designated WS, the selector includes the switchin'gfrelay H Band-"coupling .relay K for coupling it:to the common control circuit serving it.

'The common control circuit includes the 'low impedanceimp' ulsereceiving relay "A, releasere lay B "and its auxiliaries :BA andiBB, 'slow- :re'-- leasing dialling relayC, highsp'ee'd-itest relay'pTi and its .auXiIiary'TA, last'lcontactarelay LCythe relay P responsive-to a signall' for-de'termining the hundreds group in which selection' is tobe exer-' cised, steering relay' PA and a high impedance relay AA over' which ba'lanced tone signals are reverted. There are falsoitwo'idigit switches each with banks of II contacts, switch with mag net MAM and magnet operated contacts madm for registering theten's digit'fand' switch 'MB with magnet 'MBM and 'ma'gnet operated "contacts mbdm'for'registerin'g theiunits digit. Theformer switch ha's Tour wipers designated MAI .JMA I and the latter. seven"wipers idesignat'ed I MBT. 0f the 'two digitswitches wipersil and 2..

MB! are marking wipers and wiper-MA4 is con-- vidually over marking wires to contacts in the arc of wiper M of the final selector.

A detailed description will now be given of the operation of the final selector and the common control circuit. 1

The selector and common control circuit test free by reason of the battery conection to wire 11 over wipers MA2 and MBZ'at normal, contacts bal and N2. Contacts Z2112 baS are included in the test-in circuits for seven other final selectors served by the same common control circuit. When the selector is taken into use, relay A is operated and relay P may or may not be operated in series with it. If a dilferentiating signal is transmitted from the preceding selecting stage, earth will be present on the wire at this time and relay P will be short-circuited, the circuit for relay A then being from this earth over a preceding loop, the negative wire, contacts 7L3 and 20!. If the difierentiating earth is not present, relay P will be operated in a circuit from earth over its left-hand winding, contacts Z02 and lid and the preceding loop in series with relay A. When relay A operates, contact al closes a circuit 'for relay B over resistance YA, contact pat and magnet MAM. Relay B operates but the magnet does not operate in this circuit and contact bl closes circuits for relays BA and BB and lights the supervisory lamp SL. Contact 222 applies earth over the loop for relay A independently of that over relay P or the earth connected to the wire at the preceding switching stage and prevents operation of relay P in series with relay A when the signalling earth is disconnected. Contact b3 connects battery to relay K which operatesto the earth applied to wire 11 in a preceding circuit, contact b4 closes a circuit from earth over wiper MBI at normal, contact pail and wiper MAI at normal for the left-hand winding of relay C, contact b5 prepares a holding circuit for relay C during impulsing and contact b6 closes a circuit for starting the tone generator. Relay BA on operation opens all the test-in circuits and relay BB at contacts bbl and M22 opens the homing circuits for the digit switches and closes'po'ints in the selector test circuit and the circuit for the selector magnet lVl'U. Relay C operates andatcon tact cI prepares an operating circuit for magnet MAM by shunting resistance YA by the low resistance winding of relay C by means of which this relay is held during impulsing. "Contact 02' opens a point in the circuit for magnet MU to guard against operation during impulse reception. Relay K operates andlocks up at contact kljapplies a guarding earth to the holding wire 20 at contact k2, closes a point in the circuit for a busy call meter at contact k3, closes a point in the operating circuit of relay H at contact M and a point in the operating circuit of relay WS at contact k5, connects up magnet MU at contact M5 and the test circuit at contacts k! and k8.

If relay P has been operated, it will lock up over ing bankof wipers MB3 MB! to prevent op-.

eration of relays PA and T on the release of relay C when a difierentiating signal hasnot beenreceived. The non-receipt of this signal therefore mined contact position. If relay P had notubeen operated, indicating selection in the full line .arcs

of the selector, relay T would be operated on the. release of relay C and prevent movement of the selector.

The impulses of the tens digit should now be received by relay A and they are repeated at contact al in a circuit from earth over contacts 225, al, right-hand winding of relay C, contacts cl, and 10043, to battery over magnet MAM. .Magnet MAM operates and steps theswitch in accordance with the number of impulses receivedr. As soon as the switch takes its first step, the operating circuit for relay C is opened at wiper MAI and the circuits for magnet MU and relay T are prepared. Relay C remains operated during the continuance of the impulses through its righthand winding and by reason of its copper slug, and after the last impulse of the train when relay A remains steadily operated relay C releases, the resistance of relay B being too high for it to hold in series with the latter relay. The stepping off-normal of wiper MA2 disconnects the test-in circuit for as long as the common control circuit is in use and until it has been completely restored to normal. Wiper MA3 by its setting con-' nects up one of the wipers MB3 MBl. The first five contacts in the bank of wiper MA3 are commoned to contacts 6 to Iii so that any setting of switch MA will connect up the same wiper of the set MB3 MB! for either of two paired tens digits 5 and 0, wiper MBA will mark outlets corresponding to the tens digits 1 and 6 and so on. Differentiation between the'two digital values or a commoned pair is effected by means of the connection over wiper MA4, relay WS being operated for values 5 to 9 of the tens digit and remaining unoperated for values 0 to 4 of the same. -Wiper M,

the contacts in the arc of which are connected to the bank contacts of wipers MB3 M37,

is common to both sets of wipers of the selector and the marking connection is extended over this wiper and contact wsd in one or other of its positions for marking and testing the required line.

Wiper M is also common to the'two arcs of a pair wire wipers} associated with the speaking and test and differentiation between the two arcs of a pair is effected by the receipt or non-receipt of" the diiferentiatingsignal at the time the final selector is taken into use.

When relay C releases at the end of the tens train of impulses, contact 02 closes a circuit" from earth over wiper MBI at normal, contact paZ, wiper MAI off normal, contacts bbl, 02, ii, tal and k6 for magnet MU. It also applies earth to relay T so that if a difierentiating signal has been received and relay P has not been operated, relay T will be operated over the above traced circuit as far as contact 02 thence over rectifier MRA, both windings of relay T in series, wiper- MA3, the selected Wiper of the set MB3 MB'I,

consequently andin consequence the selector wipers remain in, their normal position. The windings of relay PA 7 and TA shunted in the circuit for relay T becomeenergised and the former relay operates and locksup over its. left-hand winding, early-makecontact pal and contact bl. Both windings. of relay TA. are energised and these windings are connected so that they oppose one another and the. relay does not operate and consequently the circuit for relay H is not closed. Selection. by

the selector will therefore, take place in the full.

line arcs in which the lines ofoneof the hundreds. groups, say the odd hundred, are connected.

If. a differentiating signal has not been received, relay P circuit traced for relay T will be open at contact p2, consequently relay T will not be operated and magnet MU will operate and the selector wipers will be driven to the predetermined;

contact position at the commencement of the broken line arcs. In this position a circuit for relay T will be closed over the 52nd contact in.

the arc of wiper M, the wiper, contacts 108,101, ws4, contact in the predetermined position in .the

arc of wiper Pl or P2, whichever is connected up over contact ws4, and the. shunted relays PA and TA. Relay T operates and cuts the magnet circuit. at contact tl thereby switching in winding (1) of relay TA and the windings of" relays PA and TA are energised with the before-mentioned results; The selector wipers are now positioned atthe commencement of the broken. line arcs and selection will take place in these arcs in which the lines of the even hundred group will. be con: nected. At the. end of the tens impulse train. it. has, therefore been determined in which are of a pair and in which setof arcs selection is to be made,. that is the selection. is to be made; in aparticular are of 50 outlets to the exclusionof all other arcsof 50 outlets.

Toprevent a false selection'in a broken line.

arc of an outlet marked in common with it in the full line are should the latter outlet be engaged;

it 'is: arranged to stop the selector on the 52nd or last contacts in whichever arc selection is re quired. Accordingly a test circuit isprovided over last contacts in each of the four arcs accessible over Wipers PI and P2. To enable the selector wipers to pass this position in their preliminary movement to the predetermined contact position, the test circuit over the last contacts.

isnot connected up until it has'been' determined in. which are of a pair selection is to be. made.

This connecting up is performed by'the steeringv relay PA and will be referred to later.

Consequent on the operation of relaygPA which takes place at different times accordingtd-the' difierentiating conditions mentioned; contact pal closes a circuit for the re-operationot the dialling relay C independently of wiper MAJ .and contact pa3 substitutes magnet MBM for magnet MAM in the impulse repeating circuit. Contact; pa connects relay LC in the. circuit over the commoned last contacts in the-arcs of the testwipers. The impulses of the units train of im-., pulses are now received and-are repeated to: magnet MBM by'contact al in agsimilar. manner'j to thoseof the tens-impulse trainand the'wipers";

shuntround thegright-r 1 PA, contact pat, shunt;

will be operated and the.

8;: of. switch MB.- are, set. accordance with the: units-.- digit, to select one; of 50. marking. wires. Wiper MBI, onbeing. stepped. from normal opens. thepperating circuit for relay C leavingthat relay dependent; on impulses. for its continued opera tionand wiper M132. performs a similar function;

tosthatof wiperMAl. At the end of the units impulse train, relay C releases and closes the circuit :for" magnet MU as before and prepares: the test circuit, bothatv contact 02, and the se lector is. driven in search of the marked line.

When the selector wipersleave their normal posiso that the. selector is stopped. Contact it! in its;-

front position short-circuits the high resistance winding of relay T and extends a low resistance earth over the. marking circuit to operate the; subscribers cut off relay and to mark the line; engaged. Relay 'IAoperates and'at contact ta-li; opens a.further point in the circuit for magnet. MU andat. contact taZ- operates relay Hover its; right-hand windingwhich is of high resistance. Relay'I-I locks upover itstwo windings in series,-, the left-hand winding being ofconsiderably higher; resistance than its right-hand winding,

and contact hi to earth onwire 19, applies an en gaging earth to thetest wire of the selected line; at contact hZ thereby releasing; relay T by shorticircuit, switches the-speaking'wires through and; releases relay A at contacts 713- and M, closes a locking. circuit for relay-WS, if that relay'has' been. operated, over contacts NI, 715: and ws l and at-- contact'hfi-ea-rth a wire q for the operation of a. relay in a preceding circuit for switching ina.-.; feeding: bridge as described in United' States Pat-;- ent No;- 1,971,501 granted 28th August 1934; to. W. H. Grinsted et. al. from which feeding bridge, the connection is held 'by'means'of earth applied; to the. holding wire 10. Th'e-veryhigh resistance; connection of relayI-I guards'againstfalseseizure" after theholding earth-is removed at the end of a conversation should another selector test-in. at; atthemoment, by the operation of the test relay:v in series-with a'number of parallel-connected switching relays. On the release-of relay'A,re-';-, lay B1 is. shor-t-circuited; and is released andiate contact bl releases relays BA, BB, PA and P operated and extinguishes lamp S-L. Contact 113%. releases relay K. On therelease of relay BA points in the test-in circuits for the several Se?" lectors are closedand the release of relay B13" closes homing circuits forrthe two digit switches; One-of these; circuits is from earth over wiper"v MBI, contact 17112. and mbdm. 'for magnet and when switch. MB has homed, the circuit. of; the magnet is opened at wiper MB'I at normal and earth is then extended. over this'wiper, contact paZ, wiper MAI, contacts bbl and madms'to? magnet. MAM and-switch MA is horned; Wipers: MA2 and M32- then complete the test-in circuits. Contacts bbl' and 72122 disconnect earth from contactcZ: and relay TA releases, re-impcsing a short {circuit about its winding (I) at contact ta-l andv opening; the operating: circuit for .reIayH aticontact taZ. On relay K releasing, the selector becomes disconnected from the common control circuit. The test-in circuit for the selector is maintained open at contact N2.

- At the end of the conversion when the caller clears,- earth is disconnected from wire p at the feeding bridge circuit and relay H -is released.

Contact h! disconnects relay H from wire 1), contact h2 removes the engaged marking from the called line and releases the cut-off relay thereof, contacts h3 and b4 disconnect the incoming speaking wires from the wipers and connect them to the impulse receiving relay A and relay P, contact h5 releases relay WS if that relay was operated and closes the selector homing circuit and contact 716 disconnects earth from wire q. Magnet MU operates in a circuit from earth over contacts NI, b5 and kit and the selector is homed, the magnet circuit being-opened at contact NI when .the wipers reach their normal position. Contact N2 closes in the test-in circuit to enable the selector to be taken into use for another call.

If the called line is the first line of a P. B. X group, it is marked in the arc of wiper M and tested similarly to an ordinary line. The contact in the arc of wiper M is also connected to the contacts in oneof the arcs of wipers XI and X2 corresponding to lines of the P. B. X group so that all the lines of the group will be testedover the appropriate arc of wiper XI or X2, contacts 1035, kl, wsll and the relevant P wiper. If a line of a P. B. X group other than the first line is called, there will be no connection between the are of wiper M and that of wiper XI or X2 and action will be as for a call to an ordinary line.

If an ordinary line or a numbered line other than the first of a P. B. X group or all the lines ofa P. B. X group called by dialling the number of the first line is or are found busy, the final selector continues in rotation until the last contacts in the selected arc are reached. A circuit is then completed for relay T over the last contact in the arc of wiper M, the wiper, the test wiper, last contact in the selected arc, shunted relay LC, contact p114 and shunted winding (II) of relay TA. Relays T and LC operate but relay TA does not for the reason previously given and the switch is stopped in the last contact position in the selected arc. Contacts ZcI and Z02 disconnect the incoming loop from relay A and connect it to the high impedance relay AA which operates and at contact aaI holds relay A. Contact Z03 applies busy tone over wire BT and the righthand winding of relay AA and this is repeated by induction over the other two windings of the relay and the calling loop. Battery and earth over wire BE are applied alternately to the wire to give the well known flashing signal. C'ontact Zc4 connects up a busy call meter to the wire. It may be arranged to record on this meter all ineITective calls to a particular line or group of lines and for this purpose the relevant contact in the arc of wiper M would be connected to the last contact in the relevant arc in the wire so that in the event of a busy condition being encountered earth over relay T and the marking wire will be extended over the last contact in the Wire are concerned, the wire wiper, contacts k3 and Z04 to the battery-connected busy call meter.

The arrangements shown in Fig. 3 may be used if it is desired to meter ineffective calls to particular lines or groups of lines, the lines in respect of which such metering is to be performed being connected in different arcs of the selector. In

this 'way calls to four difierent lines or groups of I lines may be. dealt with. The arrangements shown in Fig. 3 are intended to be considered as being connected below the contact led in Fig.2, the relevant contacts in the arc M being connected to the last contact in the relevant arcs in' the wire. Two additional wipers and banks of the tens digit switch are provided, these being designated MA5 and MAS and the wipers are connected to back and front contacts respectively of a change over spring set p3 or relay P. The contacts in the two additional banks of switch MA are commoned in the same manner as those in the bank of wiper MA I, i. e. contacts 5 to 9 are commoned in one group and connected to one busy call meter and contacts I to 4 and U are commoned and connected to another busy call meter, providing connections to 4 busy call meters corresponding to the 4 arcs of the selector in which selection can be exercised. Since relay P is operated for connections over one are of a pair and not. for the other, differentiation between ineffective calls ,over the two arcs of the odd or even numbered wipers is effected by contact 113 and since the contacts in the additional banks of switch MA are commoned to agree with the connections of the wiper switching relay WS in the bank of wiper MA I, diiferentiation between ineffective calls over the two sets of arcs associated respectively with the odd and even-numbered wipers is effected by the position of wiper MAS or MAG.

Release from the last contact position follows in the manner previously described, the disconnection of the holding earth from wire p releasing relays AA and A. V

I claimr 1.,In a, telephone system, a final selector switch including a'plurality of wiper. sets and sets of contacts,, subscribers lines accessible theretofsaid lines divided into four groups, each group appearing in a different set of contacts in said switch accessible to one wiper set, marking devices operated responsive to received series of impulses representing digits of a subscribers number for marking a corresponding line in each of said groups, means for determining which of the marked lines will be seized, said means responsive to a signal received independent of said impulses and to one of said series of impulses.

2. In a telephone system, a switch having wipers having access to a plurality of groups of subscribers lines each having a directory number said lines divided into four groups of contacts in the bank of said switch, marking means operated in response to impulses received in accordance with the number of the called line for marking the contacts of a line in each group, and means for selecting the group in which the marked line is to be seized by either moving the wipers to an advanced position or starting testing from a normal position and by either performing a wiper switching operation or using a normal set of wipers.

3. In a telephone system, an automatic switch having wipers and banks of contacts accessible thereto, subscribers lines connected to said banks of contacts and each having a directory number, said contacts divided into four groups, means in the switch responsive to the receipt of impulses corresponding to a subscribers number for marking a set of contacts in each group, means in the switch responsive to a received signal for rendering the markings on certain of accessible.

said 'groups ineifective, and means responsive to certain of said impulses-for rendering the mark-- motion final selector switch having a plurality of-wipers each having access to aset' of contacts, an incoming line connecting"withsaidswitch; a different group of subscribers lines connectedto each of said sets of contacts, control equipment associated-with said switch, said equipment ineluding a marking device responsive to the receiptof a train-of impulses for causing said incoming line to be connected to certain of'said wipers having access only to certain-of said-sets of contacts, means in said equipment controlled in response to asignal received prior to said trainofimpulses for'selecting-a particular set of" contactsin said certain sets for-engagement "with its respective wipers, and means-including 'a marker" switch responsive to the receipt: of

another train of impulses for causing said switch ,to connect said'incoming line to' a particularsub scriber. line. in the group of subscribers. lines connecteditogsaid particular set" of contacts;

l 5; In'a telephone system, aniautomaticswitch having two setsof wipers; two'sets of "bank: con ..ta cts'accessible'to each set'of wipers; a groupof s'ubscribersflines connected ineach set of contacts, means in the switch for marking the con-.- tacts .of a line in each group selectable responsive to received. impulses means responsive-to va received signal other. than said" received impulses for' determining the set or contacts tio be selectable by either set of wipers, and means for selecting theparticularset. oi wipers to be used to render. only one. marked set of contacts 6. Ina telephone: system an automatic switch number for determining whether ornot said re-'- Iay'is-to'be operated and for preparing a marking circuit; for part of the lines in all of said groups, asecond means in the switch operated irr response to impulses corresponding to the units digit-of said number for completing" the markingcircuittoa particular line in-the groups selected, and means" responsive: to a received signal independent-of said-impulsesfor causing only certain of said markings to be effective.

' DOUGLAS'PERCY LONG.

REFERENCES CITED l The following references are of record in the file of'this-patent:

UNITED STATES PATENTS Number" I Name Date 1,830,935 Deakilr Nov. 10, 1931 5,877,383 Kahn Sept. 20, 1932 1,903,20'11 Wi'clsetall Mar; 28;-1933 1,922,237 Escott Aug. 15, 1933 1395131341 Dixon Mar. 13, 1934 13,956,371 Christian Apr. 2'4, 1934 250135169 Patterson Sept. 3, 1935 070,999 Lubberger- Feb. 16, 1937 2*,087'398 Dixon Jll-l'y 20', 1937 2,087,405 Humphries July 20, 1937 093,242 Humphries' Sept. 14, 1937 2511403931 Wright Dec. 20,- 1938 1231 723947 Taylor- Sept. 12, 1 939 L '2',;190;14'0' Taylor et-a-T Feb. 13; 1940 Christianet al May 8,1945 

